1. Field of the Invention
The present invention relates to an appearance inspection method and an appearance inspection apparatus. More particularly, the present invention relates to an appearance inspection method and an appearance inspection apparatus for an IC package.
2. Description of the Related Art
Conventionally, the following techniques have been well known as an appearance inspection apparatus for an IC package.
Japanese Laid Open Patent Application (JP-A-Heisei, 10-213417) discloses the following method of detecting a position of an IC package. A boundary between a side surface and a top surface of a package is detected by using a histogram. The linearity of a continuous distribution of respective dots is detected from the differential values of distributions at boundary points. Also, a package boundary straight line is detected by using a least square method, from the remaining dots in which non-linear sections caused by loss are removed. Moreover, an intersection of the detected straight lines in an x-direction and a y-direction is assumed to be an origin. Then, the x, y straight lines are rotated by angles equal to each other so that an angle between the two straight lines with the origin as a center is 90 degrees. Then, an x-direction standard axis and a y-direction standard axis are calculated. Accordingly, even if there are a loss, a burr and the like, it is possible to correctly detect the IC position and also possible to correctly set a detection position of a defect item with regard to an appearance inspection, a detection position of a lead and the like.
Japanese Laid Open Patent Application (JP-A-Heisei, 11-14317) discloses the following appearance inspection method. An IC package is photographed by using a TV camera. With regard to a picture data, a scanning start area is set on the periphery of the IC package by using an area set device of a picture data processor, and the scanning is done. A position data group at an end of the IC package is detected by a position data detector. In accordance with this position data group, an inspection target region is set for the picture data by using an inspection target region set device. A picture process is done by a judging device. Then, it is judged whether the IC package is allowed or rejected.
Japanese Laid Open Patent Application (JP-A-Heisei, 7-128249) discloses the following IC extraneous substance detector. A camera photographs a lead of an inspection target IC. An AD converter carries out an AD-conversion. A differential circuit receives a light/shade picture data, and carries out a differential process so that a change point of a concentration is highlighted, and then outputs a differential picture data. A first binary circuit converts a differential picture data in an inspection target region including a plurality of leads stored in an inspection region store circuit into a binary picture data, in accordance with a preset first binary level, and outputs it. A projection circuit measures the number of xe2x80x9c1xe2x80x9d of the binary picture data in a direction parallel to a longitudinal direction of the lead, and outputs the measured data, and carries out a binary process, and then measures the number of xe2x80x9c1xe2x80x9d of the binary data in the longitudinal direction of the lead. A second binary circuit converts the measured data into a binary value. A judging circuit counts the continuous number of xe2x80x9c0xe2x80x9d and xe2x80x9c1xe2x80x9d in a second binary data, and judges as a deposition of the extraneous substance if there is the continuous numeral without a preset range between an upper limit value and a lower limit value.
Japanese Laid Open Patent Application (JP-A-Heisei, 7-37094) discloses the following picture processor. This is provided with: an editor for editing a history of a picture process program stored in a history program memory; and a corrector for deleting a duplex portion in a picture process command list and an unnecessary component to obtain a final result. An indication from which a user can understand a picture process command and learn a usage method is displayed on a display. An illumination manner suitable for a target sample is determined from an evaluation value of the result treated by the picture processor. A picture process program is generated in accordance with an evaluation value of a feature amount. Also, a function is displayed after a selection based on a combination of measurement values. Then, a function selected on the basis of the indication is added to the picture process program.
Japanese Laid Open Patent Application (JP-A-Heisei, 8-44870) discloses the following method for managing a memory of an appearance inspection apparatus. A non-volatile memory can register therein an environment data with regard to a usage condition, a kind data set for each inspected sample and a user program. The store region of the non-volatile memory is divided into many blocks of a certain size. Also, the non-volatile memory has an allocation table indicative of a correspondence relation between a content stored in each block and a stored block.
Japanese Laid Open Patent Application (JP-A-Heisel, 5-264240) discloses the following appearance inspection apparatus. This is provided with: a photographing device for photographing a pattern formed on a sample; a picture binary converter for converting a photographed picture into a binary value; a radial length measuring device for measuring a length of a pattern in a pattern portion within each of pixel rows extending in a plurality of directions from any central pixel on a binary picture; a center detector for detecting a substantial center of a pattern from the measured lengths in the plurality of directions; a coding device for converting each of the measured lengths in the plurality of directions into a radial code; and a category converter for storing therein in advance a category code indicative of a kind of a pattern form corresponding to each of the various radial codes, and selecting a category stored in accordance with the radial code converted by the coding device, and then converting into the category code. Accordingly, it detects a defect of a pattern in accordance with the category code.
Japanese Laid Open Patent Application (JP-A-Heisei, 7-229842) discloses the following apparatus for inspecting an extraneous substance of IC. This apparatus for inspecting an extraneous substance of IC is provided with: a camera for photographing an IC composed of a shoulder where a lead targeted for an inspection is located in a flat portion on a mold side, a plane on a tip side and a slope located in a middle between those portions; an AD converter for receiving a picture data from the camera, carrying out an AD conversion and outputting a light/shade picture data; an inspection region cutter for cutting an inspection region light/shade picture data in a range including all leads corresponding to one side of the IC from the light/shade picture data; a first binary converter for converting the inspection region light/shade picture data into a binary value so that only the shoulder and the plane of the lead, in which a reflection light amount received by the camera is large, become at xe2x80x9c1xe2x80x9d; a projecting device for receiving the binary picture data converted into the binary value by the first binary converter, and outputting an X projection data in which the number of xe2x80x9c1xe2x80x9d pixels in each picture pixel row in an X-direction vertical to a longitudinal direction of the lead is measured; a lead region divider for defining as a slant picture the portion corresponding to a center of the lead in a section where the X projection data in the inspection region light/shade picture data is smaller than a predetermined value, defining as a shoulder picture the portion corresponding to a portion on a mold side of the IC and having a value greater than the predetermined value, and defining as a plane picture the portion corresponding to a portion on the tip of the lead and having a value greater than the predetermined value; and a device for detecting an extraneous substance for each division region, which converts each of the shoulder picture, the slant picture and the plane picture into a binary value in accordance with a binary level peculiar to each of the pictures, identifies the xe2x80x9c1xe2x80x9d pixel as the portion of the lead, and then detects the extraneous substance deposited on the lead.
Japanese Laid Open Patent Application (JP-A-Heisei, 8-14845) discloses the following apparatus for inspecting an extraneous substance of an IC. The apparatus for inspecting an extraneous substance of an IC is provided with: a photographing device for photographing an IC targeted for an inspection and outputting an analog picture data; an AD converter for receiving the analog picture data, carrying out an AD conversion and outputting as a light/shade picture data; an inspection region cutter for receiving the light/shade picture data and cutting the light/shade picture data in a portion including all leads corresponding to one side of the IC, in a predetermined range; a memory for storing therein the cut light/shade picture data in the inspection region; a first binary converter for receiving the light/shade picture data from the memory, and converting into a binary value in accordance with a predetermined high binary level in which only a lead where an incident light amount to the photographing device is maximum is set to xe2x80x9c1xe2x80x9d, and a portion where the incident light amount is smaller than that of the lead is set at xe2x80x9c0xe2x80x9d; a first projector for receiving the binary light/shade picture data outputted by the first binary converter, and counting the number of xe2x80x9c1xe2x80x9d in a Y-direction parallel to a longitudinal direction of the lead for each position in an X-direction vertical to the longitudinal direction of the lead; a second binary converter for receiving a first projection data outputted by the first projector, and converting into a binary value in accordance with the preset high binary level in order to detect the extraneous substance on the lead; a differential device for receiving the light/shade picture data from the memory, carrying out a differential process, and outputting as a differential light/shade picture data; a third binary converter for receiving the differential light/shade picture data, and converting into a binary value in accordance with a predetermined low binary level in which only a portion between the leads where the incident light amount to the photographing device is minimum is set to xe2x80x9c0xe2x80x9d, and a portion where the incident light amount is larger than that of the portion between the leads is set at xe2x80x9c1xe2x80x9d, a second projector for receiving the binary differential light/shade picture data outputted by the third binary converter, and counting the number of xe2x80x9c1xe2x80x9d in the Y-direction for each position in the X-direction; a fourth binary converter for receiving a second projection data outputted by the second projector, and converting into a binary value in accordance with the predetermined low binary level in order to detect an extraneous substance between the leads; a detection region cutter for retrieving xe2x80x9c1xe2x80x9d in the first binary projection data outputted by the second binary converter and xe2x80x9c0xe2x80x9d in the second binary projection data outputted by the fourth binary converter, with regard to the X-direction, and determining the positions of the two xe2x80x9c0xe2x80x9d firstly located in respective outer directions with respect to the two xe2x80x9c1xe2x80x9d located at both ends, and then specifying the section between the positions of the two xe2x80x9c0xe2x80x9d as an extraneous substance detection target range; a lead extraneous substance detector for counting the continuous number of xe2x80x9c1xe2x80x9d and the continuous number of xe2x80x9c0xe2x80x9d in the first binary projection data, within the extraneous substance detection target range specified by the detection region cutter, and then judging whether or not the extraneous substance exists on the lead, in accordance with the fact whether or not they are within the predetermined ranges; and a lead-to-lead extraneous substance detector for counting the continuous number of xe2x80x9c1xe2x80x9d and the continuous number of xe2x80x9c0xe2x80x9d in the second binary projection data, within the extraneous substance detection target range specified by the detection region cutter, and then judging whether or not the extraneous substance exists between the leads, in accordance with the fact whether or not they are within the predetermined ranges.
Japanese Laid Open Patent Application (JP-A-Heisei, 11-63951) discloses the following appearance inspection apparatus. This appearance inspection apparatus is the apparatus for inspecting the appearance of a package, such as a BGA CSP type IC and the like, in which a mark is affixed on a top surface, and a terminal for electric connection is formed on a rear surface. It is provided with: a pickup for picking up the package accommodated in a tray in a manner that a terminal surface is facing downward, and then sending to a measurement position; a mark package void inspector mounted above a pickup position of the package from the tray; and a measuring device for inspecting a terminal side of the packaged sent to the measurement position in the condition that the top portion is held by the pickup, by using a picture process measurement or a laser deviation measurement. The package void inspector inspects a next package located at a pickup position in a course when the pickup sends the package after the inspection of the mark package void to the measurement position.
Japanese Laid Open Patent Application (JP-A-Heisei, 11-135054) discloses the following charged particle beam device. This charged particle beam device is provided with: a device for irradiating a charged particle beam to a sample; a sample signal detector for detecting a sample signal sent from the sample; an AD converter for converting the detection signal of the sample signal detector into a digital signal; a basic picture processor for processing the digital signal from the AD converter by using a dedicated circuit; a picture memory for storing therein as a picture data the signal processed by the basic picture processor; and a display for displaying thereon the picture data stored in the picture memory. This is further provided with a parallel picture processor including one mask CPU and a plurality of slave CPUs. The picture data stored in the picture memory is sent to the parallel picture processor. The master CPU carries out the control so that the transferred picture data is processed by the plurality of slave CPUs, in parallel, one part at a time.
Japanese Laid Open Patent Application (JP-A-Heisei, 11-259434) discloses the following parallel data processor. This parallel data processor is provided with a data input device which is driven by a drive signal sent through a drive signal bus and receives a digital signal at a predetermined first state of the drive signal; a plurality of processor elements to which the digital signal received by the data input device through a data bus is sent through the data bus; and a process distributor for communicating with the plurality of processor elements through a communication bus, at a second state of the drive signal at which the data input device does not receive the digital signal. The process distributor has a device for monitoring the states of the plurality of processor elements when the drive signal is at the second state, and determining the processor element which distributes and processes the digital signal from the data input device, depending on the monitored result.
An appearance inspection method and an appearance inspection apparatus are desirable which have a higher speed of an inspection process.
In particular, an appearance inspection method and an appearance inspection apparatus are desirable which have a higher speed of an inspection process when a plurality of inspection items are inspected.
An appearance inspection method and an appearance inspection apparatus are desirable which have a high inspection accuracy without any influence from noise component.
An appearance inspection method and an appearance inspection apparatus are desirable which agree with a property of each inspection target region.
An appearance inspection method and an appearance inspection apparatus are desirable which are convenient for a user.
The present invention is accomplished in view of the above mentioned problems. Therefore, an object of the present invention is to provide an appearance inspection method and an appearance inspection apparatus which have a higher speed of an inspection process. In particular, it is to provide an appearance inspection method and an appearance inspection apparatus which have a higher speed of an inspection process when a plurality of inspection items are inspected. Another object of the present invention is to provide an appearance inspection method and an appearance inspection apparatus which have a high inspection accuracy without any influence from noise component. Still another object of the present invention is to provide an appearance inspection method and an appearance inspection apparatus which agree with a property of each inspection target region. Still another object of the present invention is to provide an appearance inspection method and an appearance inspection apparatus which are convenient for a user.
In order to achieve an aspect of the present invention, an appearance inspection method, includes: (a) providing an image data in which an inspected sample is photographed; (b) detecting a brightness of each of a plurality of image units included in the image data based on the image data; (c) detecting the number of the image units being identical with each other in the brightness for each of the brightness; (d) detecting, as a measured maximum number, the number that is maximum of the detected numbers as a result of the (c); (e) computing the measured maximum number to determine a set maximum number; (f) determining a threshold level of the brightness based on the set maximum number; (g) converting the image data into a binary pattern based on the threshold level; and (h) detecting a defect of the inspected sample based on the binary pattern.
In this case, the set maximum number corresponds to a result when a noise component is removed from the measured maximum number.
Also in this case, the (e) is performed with first and second numbers, the first number corresponding to higher brightness with reference to the brightness corresponding to the measured maximum number, and the second number corresponding to lower brightness with reference to the brightness corresponding to the measured maximum number.
Further in this case, the (e) is performed with the brightness corresponding to the number identical with a subtracted value after subtracting a predetermined value from the measured maximum number.
In this case, a result of the (b) is represented by a histogram, and wherein in the (e), a portion in which the number is larger than a subtracted value after subtracting a predetermined value from the measured maximum number of a waveform of the histogram, is approximated to a quadratic curve, and wherein a peak value of the quadratic curve is detected as the set maximum number.
Also in this case, thr=the set maximum number X a multiplication value+an offset value, and wherein thr is the threshold level of the (f).
Further in this case, at least one of the multiplication value and the offset value is different for each of a plurality of inspection items with regard to the inspected sample.
In this case, the inspected sample is an IC package, and the plurality of inspection items include a void inspection, a detection of a package crack and a package defect, a seal inspection, an extraneous substance on a lead inspection, and an extraneous substance between leads inspection.
Also in this case, when an inspecting target area to detect the defect is smaller than a preset value, the threshold level is not determined at the (d), (e) and (f), and a predetermined standard value is used as the threshold level.
Further in this case, the inspected sample is an IC package, a concave section is formed in the IC package, the concave section being provided for a pin to push the IC package out of a mold making industry when the IC package is molded, and wherein when an inspecting target area to detect the defect is the concave section, the threshold level is not determined at the (d), (e) and (f), and two predetermined standard values are used as the threshold level, and wherein the converting of the (g) is performed two time by using the two predetermined standard values as the threshold level, respectively to produce two the binary patterns, and wherein the (h) includes detecting different kind of the defect with each other based on each of the two binary patterns, respectively.
In this case, the inspected sample is an IC package, and the IC package includes a seal, and wherein when an inspecting target area to detect the defect is the seal, the (b) includes detecting the brightness of a seal inspection portion in which the seal is expected to exist of the image data, and wherein the (c) includes detecting the number of the image units with regard to the seal inspection portion.
Also in this case, the inspected sample is an IC package, and the IC package includes a seal, and wherein a result of the (b) is represented by a histogram, and wherein when an inspecting target area to detect the defect is the seal, the (f) includes scanning a waveform of the histogram from the set maximum number as a beginning point in direction to higher brightness, and wherein the (f) includes detecting a peak value of a first upward convex curve next to a second upward convex curve including the set maximum number of the waveform as a result of the scanning, and wherein thr=(the set maximum number+the peak value)/2, and wherein thr is the threshold level of the (f).
Further in this case, the inspected sample is an IC package, and the IC package includes a seal, and wherein a result of the (b) is represented by a histogram, and wherein when an inspecting target area to detect the defect is the seal, the (f) includes scanning a waveform of the histogram from the set maximum number as a beginning point in direction to higher brightness, and wherein the (f) includes detecting a peak value of a first upward convex curve next to a downward concave portion of a second upward convex curve including the set maximum number of the waveform as a result of the scanning, and wherein thr=(the set maximum number+the peak value)/2, and wherein thr is the threshold level of the (f).
In this case, the inspected sample is an IC package, and the IC package includes a seal, and wherein a result of the (b) is represented by a histogram, and wherein when an inspecting target area to detect the defect is the seal, the (f) includes setting a range corresponding to a predetermined brightness of the histogram as a seal inspection portion, and wherein a peak value in the seal inspection portion of a waveform of the histogram is detected, and wherein thr=(the set maximum number+the peak value)/2, and wherein thr is the threshold level of the (f).
Also in this case, the inspected sample is an IC package, and the IC package includes a seal, and wherein a result of the (b) is represented by a histogram, and wherein when an inspecting target area to detect the defect is the seal, the (f) includes setting a range in which Es is the lowest point in the brightness of the histogram as a seal inspection portion, and wherein the Es=the set maximum number X a set multiplication value+a set offset value, and wherein a peak value in the seal inspection portion of a waveform of the histogram is detected, and wherein thr=(the set maximum number+the peak value)/2, and wherein thr is the threshold level of the (f).
In order to achieve another aspect of the present invention, an appearance inspection apparatus, includes: a camera photographing an inspected sample to produce an image data of the inspected sample; a threshold level providing section providing a threshold level; a binary converting section converting the image data into a binary pattern based on the threshold level; and a judging section judging whether the inspected sample is passed or failed based on the binary pattern, and wherein the threshold level providing section detects a brightness of each of a plurality of image units included in the image data based on the image data, and detects the number of the image units being identical with each other in the brightness for each of the brightness, and detects, as a measured maximum number, the number that is maximum of the detected numbers, and computes the measured maximum number to determine a set maximum number, and provides the threshold level based on the set maximum number.
In order to achieve still another aspect of the present invention, an appearance inspection apparatus, includes: an image processing library storing a plurality of image processing items; an inspection library storing a plurality of inspection item data, in which the plurality of image processing items are selected arbitrarily and in which the selected image processing items are performed in an arbitrary turn, and wherein a binary converting process is included in the plurality of image processing items, and wherein the binary converting process includes detecting a brightness of each of a plurality of image units included in an image data in which an inspected sample is photographed based on the image data, when providing a threshold level used in the binary converting process, and detecting the number of the image units being identical with each other in the brightness for each of the brightness, and detecting, as a measured maximum number, the number that is maximum of the detected numbers, and computing the measured maximum number to determine a set maximum number, and providing the threshold level based on the set maximum number.
In this case, the appearance inspection apparatus further includes: an inspection data for each kind library storing a plurality of inspection data for each kind for an inspection target product, in which the plurality of inspection item data are selected arbitrarily in which the selected inspection item data are performed in an arbitrary turn.
Also in this case, a plurality of the inspection item data includes data for a void inspection, data for a seal inspection, data for a mold loss inspection, data for an IC package direction difference detection and data for a lead curve detection.
Further in this case, a plurality of the inspection item data includes a parameter used in the computation included in the binary converting process.
In order to achieve yet still another aspect of the present invention, a computer readable recording medium for recording a program for a process, includes: (a) providing an image data in which an inspected sample is photographed; (b) detecting a brightness of each of a plurality of image units included in the image data based on the image data; (c) detecting the number of the image units being identical with each other in the brightness for each of the brightness; (d) detecting, as a measured maximum number, the number that is maximum of the detected numbers as a result of the (c); (e) computing the measured maximum number to determine a set maximum number; (f) determining a threshold level of the brightness based on the set maximum number; (g) converting the image data into a binary pattern based on the threshold level; and (h) detecting a defect of the inspected sample based on the binary pattern.
In the present invention, a picture processing algorithm (inspection algorithm) is generated in which various algorithms of pre-registered picture processes are combined and duplicated in any order by a user. The user gives any name to the duplicated picture processing algorithm, and it is registered.
The user specifies the picture processing algorithm generated uniquely as mentioned above, within an inspection data for each kind, by using the name at the time of its registration. Thus, its picture processing algorithm is commonly used even in generating a different kind of inspection data. Moreover, the picture processing algorithm is individually changed in the inspection data for each kind.
In the inspection data for each kind, the picture processing algorithm, an inspection region and a judgment value are set. At a time of an automatic inspection, the picture process is done in a specified inspection region, in accordance with a preset inspection data. A finally measured value is compared with the judgment value. Accordingly, whether it is allowed or rejected is judged.
Its inspection result is outputted to any address for each inspection item arbitrarily generated by the user.